1. Field of the Invention
The present invention relates to mechano-chemical fluorination, specifically an improved method of fullerene fluorination.
2. Invention Disclosure Statement
Fullerene Fluorides (FF) are useful and can be employed in many fields. For example in the field of medicine they have been used in AIDS research. (Volpin M. E., Belavtzeva E. M., Romanova V. S., xe2x80x9cSelf assembling of associates of amino acids and dipeptide derivatives of 60 fullerene in aqueous solution.xe2x80x9d Mendeleev Comm. 1995 129-131.) They have also been used in the synthesis of super-conductive materials and to aid in the production of nanotubes. (Haddon R. C., Hebard M. J., Nature. 350 320 (1991); Lijima S. Nature, 354 56 (1991))
To produce FF in the prior art, several conventional prior art methods are used. For example, Fullerenes C60 and C70 are known to react with elemental fluorine and chlorine, as well as with XeF2, ClF3 to form fullerene halides. Fluorination of C60 results in the formation of a mixture of compounds from C60F2 to C60F60. C60F48 is the major component of the mixture formed upon long-term fluorination. (Gahk A. A., Tuinman A. A. Adcock J. L. Tetraedron Lett. 34 (45), 7167-7170 (1993)) Fluorination of C60, upon exposure to UV radiation has been reported. (Cox D. M., Cameron S. D., Tuinman A. A., J. Am. Chem. Soc. 116 (3), 1115-1120 (1994)) Fullerene Fluoride C60 readily transfers into gas phase and can be identified by mass-spectrometry.
According to Halloway J. P., Hope E. J., Taylor R., J. Chem. Soc. Chem. Comm. 1991 (14), 966, fluorination of solid C60 with gaseous fluorine at 70xc2x0 C. for 12 days in Ni container leads to the formation of a white substance identified as C60F60. (Malkerova I. P., Secastianov A. S., Alikhanyan A. S., Dokl. Acad. Nauk., Chemistry (Russian). 342 (5), 630-634 (1995)) This can be identified using 19F NMR and IR spectra with fluorine upon exposure UV radiation. (Tuinman A. A., Gakh A. A., Adkoc J. L. xe2x80x9cFluorinated Fulerenesxe2x80x9d J. Am. Chem. Soc. 115 5885 (1993)) It is also possible to use ClF3 as the fluorinating agent. (Alikhanyn A. S., Malkerova I. P., Sevastynov D. I. et all. Zhurnal Neorgan. Khimii. (Russian) 40 (9), 1502-1509 (1995)) These prior art methods however, are impractical and inefficient. Most techniques produce a low yield of the desired product. Another problem is that these techniques are too slow to be practical. An added problem with the production of FF is that it causes corrosion of materials and containers.
U.S. Pat. No. 5,558,903 describes a method to fabricate FF films that have an improved purity and adhesion to a substrate. A sublimation method is described for preparing fullerene coatings. The process is carried out in the presence of a substrate in a fluorine flow at 450-550xc2x0 C. This invention describes the use of fullerene materials as very good lubricants. The drawback to the method described is that it produces very poor yields and low purity materials.
U.S. Pat. No. 5,382,719 describes a method to fabricate FF with fluorinate, CF straight chain hydrocarbon from 1 to 100 carbon atoms. Using this method, however, it is impossible to fabricate precise compositions such as C60F48, C60F36, or C60F18.
U.S. Pat. No. 5,510,098 describes a related method based on the CVD synthesis of doped fullerenes (including Ni, Rb, Cs, F, etc.) in large macroscopic quantities. This synthesis is relatively inexpensive and does not require the use of solid carbon materials such as graphite. Improved hot-filament-assisted chemical deposition method is used for the simultaneous deposition of diamond and fullerene on silicon substrates and other refractory metals such as W or Ta. This process creates diamond like films located in the central part of the substrate (substrate temperature xcx9c900xc2x0 C.), and fullerene soot located close to the substrate holder edge (500-700xc2x0 C.). In this invention an example is given where the pressure used in this method is between 300-100 torr. Fullerene soot (5-20 mg) is collected for 5 hours. Some drawbacks to this method however, are that the yield is only around 1 mg/hour and that the obtained FF compositions are varied.
Conventional vibromilling is used in the synthesis of some materials such as NH3 from environmental nitrogen (Ivanova T. P., Lipson A. G., Kutznetzov V. A. et all. xe2x80x9cMechano-chemical synthesis of ammonia upon titanium dispersion.xe2x80x9d News from Russian Academy of Scientific. Series of Chemistry. 42 (1), 237-238 (1993)) cement clinker at 700xc2x0 C., and high temperature superconductor YBa2Cu3O7 (Lipson A. G., Petrov S. V., Kutnetzov xe2x80x9cEffect of the mechano-activation of components on the physiochemical properties of super conducting Yttrium-barium ceramicsxe2x80x9d V. A. Dokl. Report""s Academy of Scientific USSR. 306 (6), 1409-1412 (1989)) Conventional vibromilling however, has limited application to the synthesis of FF. FF synthesis causes prior art containers and milling balls to corrode and crack. This destruction of vibromilling materials decreases the quality of synthesis results. The present invention, however has overcome these deficiencies in FF synthesis.
It is an object of the present invention to provide a method of mechano-chemical fluorination that has an increased yield.
It is also an object of the present invention to provide a method of mechano-chemical fluorination that reduces or eliminates corrosion and destruction of vibromilling materials.
It is another object of the present invention to illustrate a mechano-chemical method of synthesizing Fullerene Fluorides that is commercially practical.
Briefly stated the present invention provides a method of mechano-chemical fluorination that has a significantly improved yield over prior art methods of synthesis. The present invention illustrates this improved mechano-chemical Fluorination by describing the improved synthesis of Fullerene Fluorides (FF). This present method overcomes reduced product yield that results from vibromill material corrosion. This present method also overcomes the prior Fluorination and FF synthesis problems of the prior art by utilizing different fluorinating materials, adding catalysts and diluting agents to the process, varying milling times, and heating in the presence of inert gasses to improve the fluorination process.
The above, and other objects, features and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings.